The recent progress of computer technology is literally amazing. In the realm of hardware, the hitherto-undreamed-of high speed mathematical operation and large memory capacity have been implemented in the aftermath of a great tide of improvements in operational elements and memory elements. Particularly in the field of memory media, the early magnetic cores were replaced by semiconductor integrated circuits which are now being superseded by light elements in many applications. Advances in software are not less remarkable. Thus, ordinary computation and data processing have by now become routines and time-sharing processing backed by large memory data, such as for booking of tickets, has already been materialized.
It has also been made possible to process picture data as image data. Such a system scans a picture, inputs and stores brightness data at junctions of high-density horizontal and vertical scanning lines as digital data, searches for required data on demand and reconstructs the picture as an output. This is another technology implemented as large memory became a reality.
As such an image processing technique, there is known an image transmission system which is now a commonplace artifact closely associated with many industrial and personal activities today. Though not requiring any extraordinarily large memory, this system scans an original picture, transforms its graded pattern of shade into electrical signals and outputs them for reconstruction of the original picture at a remote receiving device. This technology is similar to the above-mentioned image processing system in that picture images are once converted to digital signals.
Regarding the storage of large volumes of documents, these are generally microfilmed and filed but research has been undertaken into a system for scanning such documents as pictures, transforming them into digital signals for storage and retrieving stored digital signals for output of picture images.
As a device emphasizing the output of a picture image, there is known the so-called karaoke device utilizing an opticomagnetic disk. This device is also worth attention in that a huge mass of video information has been accommodated in a compact disk.
As a unit technology, it is already an established procedure to transform a large number of picture elements constituting a drawing, a photograph or a document into electrical signals, store them as a package and gives an output in the form of a reconstructed picture image. By using such technologies in combination, a variety of applications can be implemented.
As a typical example, a computer-aided filing system can be mentioned. However, the filing system is adapted mainly for document search and accessible by limited persons concerned but cannot be utilized by a large number of indefinite persons. Particularly the system cannot output different data for a large number of users at any one time. This is also true with other image processing systems.